The methylgalactoside permease (MeGalP) is a multicomponent transport system of Escherichia coli K-12 which mediates the intracellular accumulation of D-galactose and closely related sugars. The genetic locus of MeGalP has been located at 45 min on the chromosome and shown to consist of four closely linked genes, mglA, B, C, and D. At present, only the product of one of the genes, mglB, has been isolated. It has been chacterized as a galactose-binding protein. Thus, the next logical step, towards the objective of understanding transport mechanisms is to identify the products of the mglA and mglC geJes (since MglD is a regulator gene, studies of MglD are not included here). Recent developments from this laboratory have provided means to detect in vivo activity of the MglA and C genes in the absence of a functional galactose-binding protein. The overall objectives in this project are: a) identification and functional characterization of the gene products of mglA and C in minicells carrying synthetic hybrid DNA; b) comparison of mglA, C-dependent transport with that requiring all three genes in order to determine the role of the galactose-binding protein; c) identification and functional characterization of a newly uncovered outer membrane component of the MeGal system.